FORT COLLINS, Colo. - Sunday is the 13th running of the Access Health Colorado Marathon in Old Town Fort Collins.

Over the years participants have raised more than $120,000 for various causes.

This year, a group of 45 people, calling themselves "Team Tanner," is "Running for Sherra."

Chris Tanner says he lost the love of his life when Sherra Tanner lost her battle with cancer.

"So we went in for a colonoscopy on a Monday morning. She was on the operating table by 11 a.m. that same day," Chris Tanner said. "It was a very aggressive form."

Sherra was just 44 when she died.

She left behind two children, Alex and Ryan.

Money raised during Sunday's marathon will help put the boys through college.

"That was Sherra's dream, be a mom and put her kids through college," said Carolyn Gdowski, who became friends with Sherra while attending the University of Northern Colorado.

"We're also raising money for the oncology nurses; very specific to the nurses that treated Sherra," Tanner said. "They're near and dear to our hearts."

"Running is hard. Fund raising is hard," Gdowski told 7NEWS Photojournalist Major King. "But, you learn from that process that you're doing good for other people, and there is healing that comes with that."

"What will [the race] be like for you?" King asked Tanner.

"Tough. It's gonna be tough. But, uh, I think I'll hold it together for the run… but when I hit the finish line it's… I have a feeling a lot's gonna come out," Tanner replied.

"You know how in life there are people who are people magnets? They just draw people in. That was Sherra," Tanner said.

"Sherra was a strong girl with a radiant smile, and that smile drew people to her, and drew people in," said Gdowski.

The American Cancer Society estimates there will be nearly a 100,000 new cases of colon cancer this year.

More than 90 percent of colon cancer is found in people 50 and older. Doctors recommend getting a colonoscopy at that age for early detection.